Watch Achilles and the Tortoise (Akiresu to kame) online

"Such a scenario occurs right from the beginning, in an animated prologue which explains the bizarre title: as pointed out by the philosopher Zeno, if Achilles (the fastest mortal man, according to Greek mythology) and a tortoise competed in a race, and the latter had even the slightest advantage (say three feet), logic demands that in the time required for Achilles to reach that point, the tortoise would keep moving forward, and therefore the famous warrior, paradoxically enough, would never be able to catch up with the notoriously slow animal"